Energy is the universal currency of life and achieving a balance between energy intake and expenditure is vital for individual and population survival and fitness. In this thesis the relationships between energy expenditure, ambient temperature, habitat, activity, and parasitism were examined. In addition, the emissivity of mammal pelage was determined for use in infrared thermography. Infrared thermography is an increasingly popular technique in medical and veterinary science but its use in quantitative physiological studies on mammals remains limited as pelage emissivity data are scarce. In this thesis pelage emissivity was measured for 23 mammal species. Mean emissivity was lower than the values recommended for mammals with no observed correlation with fur metrics. The relationship between thermal stress, habitat and physiology was examined for three species of African mole-rat from different habitats. Species which inhabited regions with the greatest fluctuations in ambient temperature (savannah and desert species) could maintain their body temperature better than the montane species which could not maintain its body temperature when ambient temperature was high. The impact of high thermal stress on animals may be exacerbated during energetically expensive activities such as hunting. Cheetah surface temperature was measured before and after exercise. There was no evidence of increased radiative heat loss in cheetahs after chases but evaporative water loss from the nasal cavity may be significant for thermoregulation. Disease plays an important role in regulating animal populations. Parasitic infection was examined in the European hedgehog in Northern Ireland and the physiological effects of parasitism were determined. Twelve parasite species infected Northern Irish hedgehogs with endoparasites and, potentially, ticks incurring the highest metabolic costs to hosts. Overall, this thesis provides an overview of the effects of potential stressors on energy expenditure in several mammal species occupying different niches. Some of these species (the cheetah and European hedgehog) are currently of conservation concern in all or part of their range. The findings contained in this thesis may therefore contribute towards conservation efforts. Furthermore, they may aid climate change researchers in predicting the effects of global warming on species occupying particular habitats or niches.

Amphibian skin secretion has been studied for over fifty years and has been considered as a treasure trove of an extraordinarily-rich variety of biologically-active compounds. Novel peptides are constantly being discovered in amphibian skin secretions and some have counterparts in mammals, thus it is commonly thought that their study is an excellent way for the discovery of new mammalian peptides. Model genomic and proteomic techniques have been applied in this study to identify and characterise several gene-encoded peptides from selected Peruvian frogs, Phyllomedusa baltea, Phyllomedusa palliata and Phyllomedu'sa tomopterna. Two novel phylloseptin peptides and three different dermaseptin peptides were identified, and their synthetic replicates exhibited different levels of antibacterial activities. Both phylloseptin and dermaseptin peptides are representative members of peptide families identified from phyllomedusine frogs. A novel dodecapeptide, which was named FR-12, was found to possess dose-dependent relaxation effects on rat ileum smooth muscle. Moreover, specifically-designed analogues showed different potencies as compared with the natural peptides and the comparisons obtained revealed that the structural parameters of antimicrobial peptides are interdependent and jointly determine their activities.

Amphibians have existed on Earth for more than 300 million years. Most amphibians can survive in a wild range of living environments. Some of their living environments are fulfilled with pathogen microorganisms. The skin of amphibians produces a complex noxious/toxic chemical cocktail from specialised granular glands to against these microorganisms. This thesis describes several novel bioactive peptides which were identified from the skin secretions of the Chinese Bamboo odorous frog, Odorrana versabilis, the Chinese Black-spotted Pond frog, Pelophylax nigromaculatus and the Eurasian edible frog, Pelophylax kl. esculentus, by using reverse phase HPLC and molecular cloning. The first discovery in this study was ornithokinin, obtained from the skin secretion of Odorrana versabilis. In addition, a novel Bowman-Birk like trypsin proteinase inhibitor peptide with strong myotropic activity, named QUB 1813, was isolated from the skin secretion of the Eurasian edible frog, Pelophylax,kl. esculentus. A novel antimicrobial peptide, esculentin-2Blm, was then isolated from the skin secretion of Pelophylax kl. esculentus. These novel antimicrobial peptides show dramatic antimicrobial activities but with associated relatively high haemolytic activities. Finally, a novel myotropic peptide, named QUB 1067, was obtained from the skin of the Chinese Black-spotted Pond frog, Pelophylax nigromaculatus. QUB 1067 has a completely novel primary structure and exhibits contractile activity on isolated rat uterus smooth muscle tissues. All of these bioactive peptides were synthesised by employing PS3 solid-phase Fmoc chemistry. The synthetic replicates were used in the bioactive assays, such as antimicrobial activity assays, haemolytic assays, smooth muscle assays and trypsin inhibitory assays.

TAR-DNA-binding protein 43 kDa (TDP-43) is an RNA/DNA binding protein that is involved in amyotrophic lateral sclerosis (ALS), frontotemporal lobar degeneration (FTLD), and a number of other neurological diseases that have been currently classified as TDP-43 proteinopathies. Defects in the control of TDP-43 expression levels may contribute to the neurodegeneration process observed in patients. TDP-43 autoregulation depends on a particular 700 nucleotides long sequence, the TOP Binding Region (TDPBR) within the TDP-43 3' UTR which contains several low affinity binding sites for TDP-43. If TDP-43 nuclear levels rise, increased binding to the TDPBR can trigger in a fraction of the nascent pre-mRNA molecules, a specific splicing event that removes the main poly(A) site, leading to an alternative poly(A) transcript that promotes mRNA instability. In the first part of this thesis I have determined that constitutive spliceosome formation across the intron 7 leads to low RNA and protein TDP-43 production. This event is in part caused by an altered nucleo-cytoplasmic distribution of the RNA. In the second part of the study, using a series of minigenes, I mapped some of the splicing cis regulatory elements within the TDPBR and the consequence of the variations of these elements in TDP-43 autoregulation. These data indicates that the elements within intron 7 act in an orchestrated way to sense the TDP-43 level variations. Furthermore, I demonstrated that the distance between the intron 7 and the pOly(A)2, can explain the reduced levels of TDP-43 observed when autoregulation is triggered. In conclusion this mechanism represents a novel type of auto-regulatory pathway to control cell viability, which acts through pre-mRNA alternative splicing and polyadenylation leading to mRNA degradation that is quite distinct from nonsense mediated decay (NMD).

Very low density lipoproteins (VLDL), low density lipoproteins (LDL) and high, density lipoproteins (HDL) were isolated from the serum of the rainbow trout (Salmo gairdneri Richardson). The HDL was the predominant fraction. Chylomicrons were also shown to be present in the VLDL fraction. The VLDL and HDL showed similar flotation characteristics to the VLDL and HDL of human but the trout LDL was of higher density than the LDL of human. The lipid composition of the trout lipoprotein fractions was shown to bear some similarities to that of human lipoproteins. A high proportion of long chain polyunsaturated fatty acids was found in each class. No immunological interrelationship was found between LDL and HDL, but VLDL contained antigenic determinants in common with both. The amino acid composition of apo LDL was similar to that of apo B of other species, while the principal apoproteins of HDL showed characteristics similar to those of human apo A-I and apo A-II. Egg lipoproteins were isolated from the serum of cod (Gadus morhua L) and trout by. precipitation with dextran.sulphate and manganous chloride. The overall lipid and protein composition of the egg lipoproteins isolated from the serum was identical to that of egg lipoproteins isolated from eggs. Both had similar subunit composition. No precursor-product relationship between the serum and egg components, similar to that of avian and amphibian species, was identified. Immunological studies have shown that the egg lipoproteins and normal serum lipoproteins of trout do not share any common apoproteins. Oestradiol treatment of the trout was shown to produce an increase in the serum VLDL and LDL concentrations in addition to the egg lipoprotein concentration. These observations suggest that a similar lipid transport mechanism to that of higher vertebrates including man is in operation in the trout.

No description available.

The androgen receptor (AR) belongs to the steroid/nuclear receptor family of ligand-activated transcription factors. Most of these receptors activate transcription through two distinct regions known as activation functions (AF). The first, AF-1, is located within the variable amino-terminal domain (NTD) and the second, AF-2, within the ligand binding domain (LBD). However, the AR is unusual amongst the steroid receptor family in that an independent AF-2 function has not been demonstrated. Transactivation by the AR is therefore dependent primarily upon AF-1. Previous work in our laboratory has shown that an amino-terminal fragment of the AR (amino acids 142 to 485) is able to interact specifically with RAP74, the large subunit of general transcription factor TFIIF. Using a series of deletion constructs, two distinct AR binding sites have been identified with RAP74, one at the amino-terminus and one at the carboxyl-terminus of the protein. Functional analyses of these interactions suggest that the interaction between the AR and the carboxyl-terminus of RAP74 is the most significant with respect to transcriptional activation by the receptor. Mutational analysis of the AR-NTD identified a six amino acid motif, PSTLSL, as being involved in RAP74 binding. In addition to RAP74, an interaction has been identified between the p160 coactivator protein SRC-1a and amino acids 142-485 of the AR. Interestingly, another high related p160 coactivator protein, TIF2, showed little or no binding to this region of the receptor. Structural analysis, using circular dichroism and fluorescence spectroscopy and sensitivity to protease digestion, indicates that the AR-NTD exists in an extended conformation in aqueous solution but retains a propensity to fold into a more ordered structure in the presence of the hydrophobic solvent trifluoroethanolor the osmolyte trimethylamine-N-oxide. Significantly, RAP74 also confers protection to trypsin digestion, consistent with folding of the AR-NTD (aa 142 to 485) upon interaction with a target factor.

No description available.

No description available.

No description available.